We did ours 30 years ago, ripping off the plaster and strapping. It was replaced with 2X4s FG and DW.Just consider the cost benefit.
How much do you pay in heat/cooling per year today?
How much do you expect to save per year?
How much will it cost to insulate?
Example 1, say you pay 6K per year to heat and cool the house.
Insulating will drop that by say 33% (no idea just a number).
Total project will cost 20K (again just a number).
In the above the savings are 2K per year in heating and cooling. It will take roughly 20 years to break even (ignoring TVM), even the government would have a hard time justifying that ROI.
Example 2, 4K in heating and cooling per year
Say 33% savings again (IDK, just a number)
Total project cost 50K
We get a savings of 1.3K per year but an ROI of 38 years, much longer with TVM.
Positive game changers, possible gov rebates, increasing energy costs, and possibly the increase value of the house, but that is only when/if it is sold.... and covering brick may make it a wash in value, IDK.
Negative game changers, TVM and interest on the initial costs (loan or lost opportunity).
Low hanging fruit is air sealing, specially doors and windows...
As another example, in the context of the above calcs is a high efficiency furnace:
Old furnace is running at 85%
New one will be 95%
Current heating costs are say 4K per year.
New heating costs will be around $3.6K, saving $400 per year.
New furnace with install 3K
ROI is 7.5 years (ignoring TVM which makes it longer) assuming the old furnace does not need to be replaced of course.
DIY it was worth it. Assume about 1500 SF of drywall with associated lumber, insulation and vapour barrier. I don't know if $20 per linear foot covers it but it would be around $3600 for ours.
I measured the temperature of the dining room wall (67°F) and the living room (63°F). The living room is the only room not done. I approximate a 2 watt per square foot higher energy cost for the LR. That would equate to running two plug in electric heaters all winter and possibly affect part of the summer if air conditioning is similarly used.
Comfort factor: Your body radiates heat towards a cold object and even if the air temperature is decent you will feel cold. Warm the wall and you can set the thermostat lower.
Power outage: Well insulated gives you more time before you have to set fire to the piano.
Resale value would be minimally affected. People pay for square footage and to a small degree, bling.
To pay someone to do the job doesn't make financial sense. Add a zero? Your best ROI is high efficiency heating.
Obviously if you going to do a gut and rebuild the upgrades fall right into place.